High-Spin States in Odd–Odd¹⁶⁸Lu

Abstract

We observed four rotational bands in 168 Lu using the 159 Tb( 13 C,4n) 168 Lu reaction at 58.5 MeV and 62 MeV and populated high spin states up to 27 h " . On the basis of the X-gating procedure and excitation function measurements done at beam energies of 50, 55, 58.5, 60, 62 and 64 MeV, we could identify the -ray transitions belonging to 168 Lu. The configurations of two strongly populated rotational bands (bands A and B) were based on our previous study and were examined by using the additivity relation for alignments. The configurations of two newly found rotational bands (bands C and D) were also assigned by the additivity relation. These identified configurations were confirmed by the Drissi's recipe and energy systematics of neighboring odd-odd nuclei. The configuration of bands A was assigned as K ¼ 6 þ ½7=2 þ ½404 þ 5=2 þ ½642. The configurations of the previous reported band B and two new bands C and D are likely to be 3 À ½1=2 À ½541 þ 5=2 þ ½642, 7 À ½9=2 À ½514þ 5=2 þ ½642 and 5 þ ½5=2 þ ½402 þ 5=2 þ ½642, respectively. We observed band crossing for three bands A, C and D, but not for band B. The extracted band crossing frequencies were consistent with the neutron BC crossing observed in neighboring odd-odd nuclei as well as odd-N and even-Z nuclei in this mass region. This was attributed to the occupied 5=2 þ ½642 Nilsson configuration arising from the neutron i 13=2 orbital. Energy systematics of bands built on g 7=2 i 13=2 and h 11=2 i 13=2 in neighboring odd-odd nuclei were also studied in comparison with bands A and C in 168 Lu.